[gameplay] Rework attack forge techs
- Remove the specialised infantry/cavalry attack technologies, in favour of generalist melee/ranged techs to make it easier to switch army compositions.
- Lower the costs of the technologies substantially.
- Make melee techs cost Food/Metal and Ranged techs Wood/Metal, like resistance techs.
- City phase upgrades take 60s
- New names and descriptions for the ranged attack technologies.
Differential Revision: https://code.wildfiregames.com/D3366